Advanced Placement (AP) Biology Practice Exam

What does a karyotype display?

1. The function of genes on a chromosome

2. The arrangement of chromosome pairs by size and shape

3. The number of chromosomes in somatic cells

4. The sequence of alleles in gametes

The correct answer is: The arrangement of chromosome pairs by size and shape

A karyotype is a visual representation of the complete set of chromosomes in an organism. It involves arranging the chromosomes in pairs based on size and shape. This organization allows for the identification of chromosomal abnormalities, as it provides a comprehensive overview of the chromosomal composition, including any variations in number or structure. By analyzing a karyotype, researchers can observe homologous pairs and gain insights into genetic disorders or species differentiation based on chromosomal characteristics. The other options do not accurately describe what a karyotype represents. While the function of genes and the sequence of alleles are essential to understanding genetics, these aspects are not depicted in a karyotype. Similarly, while a karyotype does provide information about the number of chromosomes, its primary feature is the arrangement and pairing of those chromosomes, making the arrangement of chromosome pairs by size and shape the most encompassing and accurate description.